FLCH 250 below 10,000 ft

[RandomPerson8008]

Hi,

Would you be chastised at your airline for flying in FLCH (or any vertical mode I guess) at 250 knots speed selected below 10,000 ft on descent because it's "too close to the speed limit"? Assume it's a calm day, smooth air, and the autopilot is maintaining the speed very accurately.

Thanks for the feedback.

[esreverlluf]

No. . . . .

[andmiz]

No. Absolutely not. It's your responsibility to maintain a speed below that limit, not the use of automation (FLCH).

[RAT 5]

RP8008: Different countries different attitudes. ATC that is; which is what this is really all about. Boeing FMC's used to (may still do) default 240/100 to allow a 10kts overspeed. VNAV would control that. There is a perception, true or not, that some ATC's allow +/-10kts. High density STAR's use accurate speed for spacing & traffic flow, and they want absolute. Use what is necessary.

[galaxy flyer]

You likely get 10 (km/h or mph) on the interstate or motorway, what’s the problem. I can understand and agree with a desire for precision, but be practical.

Inbound to MDW, behind the ever-speeding Southwest B737, ATC asked my speed, “250 knots” which is exactly what was assigned and indicated. Southwest, “what’s your speed?”; “250 knots”. ORD; “Southwest, pick it up, your 250 knots is slower than the guy behind you”. Classic.

[AerocatS2A]

We use level change with 250 selected and don’t get too bothered unless the speed is fluctuating by more than 5 knots, in which case most of us will wind the speed back a little.

[EI_DVM]

Just curious, but if ATC asked you to fly a speed of say 220kts, would you bug 210kts, incase the aircraft went too fast, or 230 kts incase it flew too slow, or just bug 220kts and accept that deviations are going to occur as we fly in a dynamic atmosphere but as long as the speed returns to target within a reasonable period of time and you don't contineously bust it then you've got the big picture covered and won't mess up ATC's spacing?

On a seperate point are there many places other than the USA that really strictly enforce the 250/FL100 rule? In Europe it's almost a daily occurrence to be asked to keep 280/300/330kts as long as you can for spacing with traffic behind/sequencing depending on how busy the airport is and where you are in the queue. Europe seems to treat 250/FL100 as more of a guideline than a speed limit.

[RandomPerson8008]

I agree with all of you. I was recently critiqued on this point during an annual observation for flying exactly 250, and in a multi-decade flying career had never been questioned on it before. I was just wondering if I had somehow missed out on a bit of airmanship or if my observer was just being overly critical.

Yes, many countries are strict about 250 below 10,000, especially Germany in my experience. They will often deny high speed climb even to a 747 or MD11, both of which often need to be 270+ to climb clean, necessitating that you leave flaps down until reaching 10,000 on climb out at heavy weights.

However, in the USA I would cite this section of the Aeronautical Information Manual (not regulatory, but advisory in nature):

4−4−12. Speed Adjustments
a. ATC will issue speed adjustments to pilots of
radar−controlled aircraft to achieve or maintain
required or desire spacing.
b. ATC will express all speed adjustments in
terms of knots based on indicated airspeed (IAS) in
5 or 10 knot increments except that at or above FL
240 speeds may be expressed in terms of Mach
numbers in 0.01 increments. The use of Mach
AIM 10/12/17
4−4−8 ATC Clearances and Aircraft Separation
numbers is restricted to turbojet aircraft with Mach
meters.
c. Pilots complying with speed adjustments are
expected to maintain a speed within plus or minus
10 knots or 0.02 Mach number of the specified speed.
d. When ATC assigns speed adjustments, it will
be in accordance with the following recommended
minimums:
1. To aircraft operating between FL 280 and
10,000 feet, a speed not less than 250 knots or the
equivalent Mach number.
NOTE−
1. On a standard day the Mach numbers equivalent to
250 knots CAS (subject to minor variations) are:
FL 240−0.6
FL 250−0.61
FL 260−0.62
FL 270−0.64
FL 280−0.65
FL 290−0.66.
2. When an operational advantage will be realized, speeds
lower than the recommended minima may be applied.
2. To arriving turbojet aircraft operating below
10,000 feet:
(a) A speed not less than 210 knots, except;
(b) Within 20 flying miles of the airport of
intended landing, a speed not less than 170 knots.
3. To arriving reciprocating engine or turboprop
aircraft within 20 flying miles of the runway
threshold of the airport of intended landing, a speed
not less than 150 knots.
4. To departing aircraft:
(a) Turbojet aircraft, a speed not less than
230 knots.
(b) Reciprocating engine aircraft, a speed not
less than 150 knots.
e. When ATC combines a speed adjustment with
a descent clearance, the sequence of delivery, with the
word “then” between, indicates the expected order of
execution.
EXAMPLE−
1. Descend and maintain (altitude); then, reduce speed to
(speed).
2. Reduce speed to (speed); then, descend and maintain
(altitude).
NOTE−
The maximum speeds below 10,000 feet as established in
14 CFR Section 91.117 still apply. If there is any doubt
concerning the manner in which such a clearance is to be
executed, request clarification from ATC.

[Piltdown Man]

All of the buttons and modes are there to be used. With some modes and under certain circumstances you have to be a bit more careful, but that is what we are paid for. FLCH below FL100 at 250 KTS is not one of those modes where extra vigilance has to be invested.

[Denti]

Interesting that you cite germany with the speed limit. In class C airspace there is no speedlimit at all below FL100 and that is used at all bigger airports in germany. Of course, if you still follow a SID there might be a specific speed restriction on that SID, even then i do get, without asking, more often than not a „high speed approved“.

[RandomPerson8008]

It's probably because most of my flights in Germany do not use the major airports. We have been instructed to always ask before exceeding 250 below 10,000ft MSL for a clean climb in Germany due to the frequency with which they deny the request, although on my current aircraft type it's not necessary for a clean climb anyway.

[Denti]

That does make sense then. You have to be able to see and avoid as you will most probably pass through class E airspace where you might encounter airplanes that are not in contact with ATC and, in the case of gliders, do not need a transponder either. ATC therefore cannot provide traffic information and of course no separation either, both of which are possible in class C. Class D (also used) would not assure separation either. An up to date map of the airspace structure helps there, which is the norm on the LIDO AFC, dunno about Jepp.

[RAT 5]

Never understood the Class E thing in Germany around busy commercial jet airports. Under Health & Safety rules the tiniest noncompliance of hi-vis jackets etc. are met with anger & indignation. How can you be zo ztupid?
Yet allowing not communicative amateurs to mix it at high speed with ATC controlled pax jest seems perfectly safe. The patients have taken over the asylum.

[Denti]

Well, the really busy airports do have protected airspace around it, the extent if that airspace is re-evaluated each year based on traffic numbers, airprox reports and airspace needs by other users. Just for perspective, there are around seven times more glider planes in germany than commercial jets, around four times more glider pilots than those flying those jets. That is a very big lobby group, not to mention substantial numbers of ultralight (not governed by EASA) and “normal” other airspace users. And of course the military wants to play as well and low level is done purely VFR (don’t fly between 1000’ to 1500’, thats the playground of those 450 kts VFR guys during the week and during office hours).

The high viz vest thing seems to be more of a british thing, not really much of an issue at most german airports.